Honda,Serpentine belt shredded after I replaced it and the tensioner (both new).

I got a new tensioner and belt and put them on. I started the engine let run for 15 seconds turn it off. I noticed that It was making the same squeaking noise as before, i checked it again and the tensioner was loose, so I tightened it up started the engine. It was still squeaking, I drove around the block,while driving I was smelling it shred. I parked it cause I don't know what else could be wrong with it. I was wondering if you could help me out? Thanks,Corey

My car has 188781miles.
My car has an automatic transmission.